This invention relates to a transducer assembly adapted to oscillate at an ultrasonic frequency for modulating a jet stream of fluid expelled through a nozzle for cleaning articles such as semiconductor wafers.
Cleaning systems for use in manufacturing semiconductor devices effectively utilize ultrasonic energy which is propagated into standard chemical solutions by transducer crystals. The crystals may oscillate at an ultrasonic frequency in the range of between about 0.2 and 5 MHz. Such cleaning systems are known as "megasonic" cleaning systems. These systems are known to remove particles down to at least 0.3 micrometer in diameter from the surface of semiconductor wafers together with organic surface film, ionic impurities, and many other contaminants. A megasonic cleaning system for cleaning both surfaces of a wafer simultaneously is disclosed in U.S. Pat. No. 3,893,869 issued to A. Mayer and S. Shwartzman on July 8, 1975 and assigned to RCA Corporation.
There is a need in the art for certain applicatons for a system using the megasonic cleaning principle without the need of immersing the articles to be cleaned in a tank or container of cleaning fluid.